Surging energy consumption and environmental concerns demand production of chemicals and biofuel through sustainable and renewable approaches. Fatty acid derived fuels and chemicals, such as alkanes and alkenes, are of particular interest to directly replace fossil hydrocarbons (P. P. Peralta-Yahya et al., Nature 488, 320, 2012; R. M. Lennen et al, Curr Opin Biotechnol 24, 1044, 2013). Since the recent discovery of an aldehyde decarbonylase which catalyzes alkane synthesis from fatty acid metabolites (A. Schirmer et al., Science 329, 559, 2010), numerous efforts have been devoted to produce alkanes using engineered microbes from renewable raw materials (Y. J. Choi et al., Nature 502, 571, 2013; T. P. Howard et al., P Natl Acad Sci USA 110, 7636, 2013; C. Andre et al., P Natl Acad Sci USA 110, 3191, 2013). Although routes to bio-hydrocarbons are emerging, a major challenge is to identify biocatalysts which are capable of producing hydrocarbons with desired carbon chain lengths and functionalities (M. K. Akhtar et al., Proc Natl Acad Sci USA, 110, 87, 2013; Y. Qiu et al., Proc Natl Acad Sci USA 109, 14858, 2012).
Medium-chain hydrocarbons are “drop-in” ready fuels with superior properties such as high energy content, low freezing point, easy product recovery, and compatibility with the existing transportation infrastructure. Possessing a derivable terminal functionality (P. S. Coelho et al., Science 339, 307, 2013), aliphatic medium-chain 1-alkenes (MCAEs) show clear advantage over other hydrocarbons as “green” precursors to industrial chemicals such as lubricants and pesticides. MCAEs, also known as medium-chain terminal olefins, are naturally produced in low abundance by diverse species as “volatile organic compounds” (VOCs) with obscure biological functions (S. Schulz et al., Nat Prod Rep 24, 814, 2007).
Despite the high value of MCAEs, nothing is known about the biosynthesis of MCAEs in organisms at either the genetic or biochemical levels. Discovery and characterization of biosynthetic pathway of MCAEs is therefore an indispensable first step towards the bioproduction of MCAEs and MCAE-derived chemicals. There exists a need for the bioproduction of 1-alkenes/terminal olefins from fatty acids.